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W Richards

Publications and source records attributed to W Richards.

At least 127 records · Page 7Linked to original sources
PubMed1972

Disparity masking.

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Depth Perception↗
PubMed1972

Disparity processing of spatial frequencies in man.

1. Adaptation to a high-contrast sine-wave grating has been shown previously by Blakemore & Campbell (1969) to raise the modulation required to detect a low-contrast grating that has the same or similar spatial frequency as the adapting grating.2. A similar adaptation effect occurs when the adaptation and test gratings are seen binocularly and are presented off the plane of fixation. When the gratings are not located on the plane of fixation, however, the greatest rise in threshold following adaptation occurs for test gratings presented in the same plane as the adapting grating. Thus, the neural mechanisms adapted to the high contrast patterns must be processing disparity information.3. The spatial frequency response of the disparity adaptation effect has been measured by adapting to gratings of different spatial frequencies presented at a given disparity, and comparing threshold elevations for identical test gratings presented in the same (disparate) plane as the adapting grating or in the plane of fixation.4. The unbiased adaptation effect specific to disparity is greatest for gratings whose periods are twice the disparity.5. There is no adaptation effect specific to disparity for individuals possessing only convergent or only divergent disparity mechanisms.6. The results suggest that disparity mechanisms make bar by bar correlations as opposed to edge by edge correlations and that narrow bar detectors feed small disparity mechanisms whereas wide bar detectors feed large disparity mechanisms.

Adaptation, Physiological↗
PubMed1971

Anomalous retinal pathways in the Siamese cat: an inadequate substrate for normal bioncular vision.

All major retinal pathways in the Siamese cat are abnormal, with almost total crossing of the projections to the pretectum and superior colliculus. These projections represent a marked disruption in the customary neural substrate for binocular vision, which implies a consequent impairment in stereoscopic depth perception. Crossed eyes, commonly seen in the Siamese cat, may therefore arise from a neuroanatomical defect in the primary visual pathways.

Animals↗